Diseases of Malabsorption Flashcards
What is celiac disease?
A digestive disease that damages the small intestine and interferes with absorption of nutrients from food
What can people with celiac disease not tolerate?
Gluten: a protein in wheat rye and barley
What occurs when celiac patients ingest gluten?
Their immune system destroy villi in the SI
What is a malabsorption disease?
Nutrients are not properly absorbed
What are the general symptoms of celiac disease in children and adults?
Children: digestive symptoms
Adults: less likely to have digestive symptoms
What is tested for in the blood for those with celiac disease?
Anti-tissue transglutaminase antibodies (tTGA)
Anti-endomysium antibodies (EMA)
If blood tests and symptoms suggest celiac disease what is done next?
Intestinal biopsy
What antibiotic controls the rash symptoms of dermatitis herpetiformis?
Dapsone
What is the only treatment for celiac disease?
A gluten free diet
What is refractory celiac disease?
When a patient has damaged unrepairable small intestines and do not absorb nutrients
Without treatment, what can people with celiac disease develop?
Osteoporosis
Anemia
Cancer
What is congenital sucrose-isomaltase deficiency?
The inability to break down sugars sucrose and maltose
What type of sugars are sucrose and maltose and where are they found respectively?
Disaccharides
Sucrose: fruits (glucose and fructose)
Maltose: grains (2 glucose)
When does sucrose-isomaltase deficiency become apparent?
When a child is weaned and beginning to eat fruit juices and grains
What is the mutation in SI deficiency?
SI gene
What is the inheritance pattern for SI deficiency?
Autosomal recessive
What type of disease is Crohn’s disease?
Inflammatory bowel disease
What does Crohn’s disease typically affect?
Ileum and beginning of colon
General symptoms of Crohn’s disease?
Diarrhea
Rectal bleeding
Urgent BM
How does Crohn’s cause inflammation?
Immune attack against healthy bacteria
What is ulcerative colitis?
Lining of the colon becomes inflamed and develops tiny ulcers producing pus and mucous
What causes the symptoms of ulcerative colitis?
WBC mounting attack against food, bacteria causing inflammation in the lining of the intestines
Major difference between Crohn’s and ulcerative colitis?
Crohn’s: can affect any part of intestines and any layer of it
Ulcerative colitis: only affects lining of the colon
Signs and symptoms of ulcerative colitis?
Loose urgent BM
Bloody stool
Diarrhea
Tests for Crohn’s:
Blood and stool
X-rays of upper and lower GI with barium
Endoscopy and biopsy
What does medication do treat Crohn’s disease?
Suppress immune system’s abnormal inflammatory response
What are 5 drugs that are to treat Crohn’s?
Aminosalicylates (5-ASA) Antibiotics Biologic therapies Corticosteroids Immunomodulators
What is Hartnup disorder?
Inherited metabolic condition that involves the transport of certain AAs in the SI and kidneys
Symptoms of Hartnup?
Mood change Nervous system problems Skin rash when exposed to sunlight Short stature Uncoordinated movements
Tests for Hartnup?
Urine test that has high levels of neutral AA and normal levels of other AA
Gene testing for Hartnup disease?
SLC6A19
Hartnup disease treatments?
Avoid sunlight
High-protein diet
Supplements of nicotinamide
Antidepressant or mood stabilizers
Complications of Hartnup?
Changes in skin color that are permanent
What does SLC6A19 code for?
A sodium-dependent and chloride-independent neutral amino acid transporter
Where is SLC6A19 found?
5p15.33
How many mutations in SLC6A19 can cause Hartnup disorders?
Six
Four phases of nutrient absorption:
Intraluminal
Terminal
Transepithelial
Lymphatic transport of absorbed lipids
Intraluminal digestion:
Proteins, carbs, fat broken down into forms able to be absorbed
Terminal digestion:
Hydrolysis of carbs and peptides by disaccharidases and peptidases in the brush border
Transepithelial digestion:
Nutrients, fluids, electrolytes transported across and processed within SI epithelium
Skin disease caused by celiac disease:
Dermatitis herpetiformis
Secretory diarrhea:
Isotonic stool and persists during fasting
Osmotic diarrhea:
Lactase deficiency, excessive osmotic forces; diarrhea fluid more than 50 mOsm more concentrated than plasma, stops with fasting
Malabsorptive diarrhea:
Associated with steatorrhea; relieved by fasting
Exudative diarrhea:
Inflammatory disease purulent bloody stools that continue during fasting
Disease producing component in Celiac disease:
Gliadin
What does Gliadin induce?
IL-15
What does IL-15 trigger?
Activation and proliferation of CD8+ intraepithelial lymphocytes
What do the CD8+ intraepithelial lymphocytes express?
NKG2D (receptor for MIC-A)
What occurs to lymphocytes that express MIC-A?
They are attacked by NKG2D-expressing intraepithelial lymphocytes
What occurs once the enterocytes expressing MIC-A are damaged?
Gliadin peptides are able to get into the lamina propria and are deaminated by tissue transglutaminase
When do cells produce MIC-A?
When they are stressed
What do Gliadin peptides cause once inside the lamina propria?
Interact with HLA-DQ2 or HLA-DQ8 stimulating CD4+ T cells to produce cytokines contributing to tissue damage
What HLA do all people with celiac carry?
Class II HLA-DQ2 or HLA-HQ8
